Microsoft’s Office division should “be prepared” for an explosion of productivity on tablet PCs, a high-level executive said this week.

DelBene

While it’s too early to tell what will happen in mobile productivity, slates hold the most possibility for using Word, Excel, PowerPoint and others, Office division President Kurt DelBene said Wednesday. And Microsoft needs to be ready.

“I think it’s open as to whether we get to a point where people do long, rich editing on mobile devices,” he said in an interview with seattlepi.com.

Not Microsoft nor any other company has brought a true iPad competitor to market, and as Apple runs away with the tablet lead, it has a chance to capture how productivity happens on its tablet ecosystem. The company released a version of iWork, its productivity suite, for iOS two weeks ago, and this week announced iCloud for – among other uses – online storage and syncing of documents.

Meanwhile, Microsoft hasn’t said anything about releasing Office for the iPad. There’s no doubting Microsoft has the de facto standard for productivity software in Office, but alternatives such as OpenOffice and Google Docs recently have been gaining steam. Such alternatives, including iWork, could have dangerous momentum by the time Microsoft gets any real Windows-based iPad competitors out there.

Two weeks ago, Microsoft showed Office on a Windows 8 tablet, but with the familiar point-and-click desktop interface. Microsoft also is keeping mum about optimizing Office for touch-screen slates. But the software giant is likely to use Office as a unique value proposition for future Windows tablets.

Microsoft has, however, put Office on Windows Phone 7 and pushed it as a key feature of the new mobile operating system, released in winter. So how have people been using Office on mobile devices so far?

“The first thing that you want to do is make sure you have a good email and calendering option,” DelBene said. Though iOS, Google’s Android, Research in Motion’s BlackBerry and others support Exchange server, Microsoft is in the best position to make the best implementation, he said.

While Exchange is the most-used Office product in mobile devices, DelBene said, Microsoft has found the next is viewing documents. (Not editing, but viewing.) People also are using OneNote, baked into Windows Phone and recently released for the iPhone, for notetaking.

Finally, a small percentage of Windows Phone users are doing light editing with the Office apps, DelBene said. The lightweight applications are good for quick edits, but don’t compare to the desktop version of Office.

But will people really want to use smart phones and tablets, with their small screens and touch interfaces, for long-form productivity? Even with a keyboard dock for a slate?

That’s something time will tell, DelBene said. “I think the industry is in a transition.”